Flow control device of a helically-shaped intake port

ABSTRACT

A helically-shaped intake port comprising a helical portion formed around intake valve, and a substantially straight inlet passage portion tangentially connected to the helical portion. A bypass passage is branched off from the inlet passage portion and connected to the helical portion. A rotary valve is arranged in the bypass passage and actuated by a vacuum operated diaphragm apparatus. The vacuum chamber of the diaphragm apparatus is connected to the interior of the intake manifold via a vacuum port and a check valve cooperating with the vacuum port. The check valve opens the vacuum port when the level of vacuum in the intake manifold becomes greater than that of vacuum in the vacuum chamber. In addition, the vacuum chamber is connected to the atmosphere via an atmosphere port and an air valve cooperating with the atmosphere port. The air valve opens the atmosphere port when the level of vacuum in the venturi portion of the carburetor becomes greater than a predetermined level for opening the rotary valve. The atmosphere port has a flow area which is slightly larger than that of the vacuum port.

BACKGROUND OF THE INVENTION

The present invention relates to a flow control device of ahelically-shaped intake port of an internal combustion engine.

A helically-shaped intake port normally comprises a helical portionformed around the intake valve of an engine, and a substantiallystraight inlet passage portion tangentially connected to the helicalportion. However, if such a helically-shaped intake port is so formedthat a strong swirl motion is created in the combustion chamber of anengine when the engine is operating at a low speed under a light load,that is, when the amount of air fed into the cylinder of the engine issmall, since air flowing within the helically-shaped intake port issubjected to a great flow resistance, a problem occurs in that thevolumetric efficiency is reduced when the engine is operating at a highspeed under a heavy load, that is, when the amount of air fed into thecylinder of the engine is large.

In order to eliminate such a problem, the inventor has proposed a flowcontrol device in which a bypass passage, branched off from the inletpassage portion and connected to the helix terminating portion of thehelical portion, is formed in the cylinder head of an engine. A normallyclosed type flow control valve, actuated by an actuator, is arranged inthe bypass passage and opened under the operation of the actuator whenthe amount of air fed into the cylinder of the engine is larger than apredetermined amount. In this flow control device, when the amount ofair fed into the cylinder of the engine is large, that is, when theengine is operating under a heavy load at a high speed, part of the airintroduced into the inlet passage portion is fed into the helicalportion of the helically-shaped intake port via the bypass passage. Thisreduces the flow resistance of the helically-shaped intake port thus,enabling high volumetric efficiency. This flow control device, however,is just the embodiment of the basic principle of operation. In order tocommercialize such a flow control device, various problems remain to besolved, for example, how to reduce manufacturing time and manufacturingcost, how to easily manufacture the flow control device, and how toobtain a reliable flow control device operation.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a flow control devicewith a helically-shaped intake port, which has a construction suited forcommercializing the basic principle of operation proposed by theinventor.

According to the present invention, there is provided a device forcontrolling the flow in a helically-shaped intake port of an internalcombustion engine which has an intake passage connected to said intakeport and has a carburetor having a venturi portion, said intake portcomprising a helical portion formed around an intake valve, and asubstantially straight inlet passage portion tangentially connected tothe helical portion and having a helix terminating portion, said devicecomprising: a bypass passage branched off from the inlet passage portionand connected to the helix terminating portion of the helical portion;normally closed valve means arranged in said bypass passage forcontrolling the flow area of said bypass passage; a vacuum operatedapparatus having a vacuum chamber and connected to said valve means foractuating said valve means in response to a change in the level ofvacuum produced in said vacuum chamber; and control means having avacuum port which interconnects said vacuum chamber to said intakepassage, a check valve which cooperates with said vacuum port and openssaid vacuum port when the level of vacuum in said intake passage becomesgreater than that of vacuum in said vacuum chamber, an atmosphere portwhich interconnects said vacuum chamber to the atmosphere and has a flowarea which is slightly larger than that of said vacuum port, a vacuumcavity connected to the venturi portion of said carburetor, and an airvalve which cooperates with said atmosphere port and is actuated inresponse to a change in the level of vacuum produced in said valvecavity for opening said atmosphere port to open said valve means whenthe level of vacuum in said venturi portion becomes greater than apredetermined level.

The present invention may be more fully understood from the descriptionof a preferred embodiment of the invention set forth below, togetherwith the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

FIG. 1 is a plan view of an internal combustion engine according to thepresent invention;

FIG. 2 is a cross-sectional view taken along the line II--II in FIG. 1;

FIG. 3 is a perspective view schematically illustrating the shape of ahelically-shaped intake port;

FIG. 4 is a plan view of FIG. 3;

FIG. 5 is a cross-sectional view taken along the bypass passage in FIG.3;

FIG. 6 is a cross-sectional view taken along the line VI--VI in FIG. 4;

FIG. 7 is a cross-sectional view taken along the line VII--VII in FIG.4;

FIG. 8 is a cross-sectional view taken along the line VIII--VIII in FIG.4;

FIG. 9 is a perspective view of a rotary valve; and

FIG. 10 is a view illustrating the entirety of a flow control device.

DESCRIPTION OF A PREFERRED EMBODIMENT

Referring to FIGS. 1 and 2, reference numeral 1 designates a cylinderblock, 2 a piston reciprocally movable in the cylinder block 1, 3 acylinder head fixed onto the cylinder block 1, and 4 a combustionchamber formed between the piston 2 and the cylinder head 3; 5designates an intake valve, 6 a helically-shaped intake port formed inthe cylinder head, 7 an exhaust valve, and 8 an exhaust port formed inthe cylinder head 3. A spark plug (not shown) is arranged in thecombustion chamber 4.

FIGS. 3 through 5 schematically illustrate the shape of thehelically-shaped intake port 6 illustrated in FIG. 2. As illustrated inFIG. 4, the helically-shaped intake port 6 comprises an inlet passageportion A the longitudinal central axis of which is slightly curved, anda helical portion B formed around the valve stem of the intake valve 5.The inlet passage portion A is tangentially connected to the helicalportion B. As illustrated in FIGS. 3, 4, and 7, the side wall 9 of theinlet passage portion A, which is located near the helix axis b, has onits upper portion an inclined wall portion 9a which is arranged to bedirected downwards. The width of the inclined wall portion 9a isgradually increased towards the helical portion B, and as is illustratedin FIG. 7, the entire portion of the side wall 9 is inclined at theconnectig portion of the inlet passage portion A and the helical portionB. The upper half of the side wall 9 is smoothly connected to thecircumferential wall of a cylindrical projection 11 (FIG. 2) which isformed on the upper wall of the intake port 6 at a position locatedaround a valve guide 10 of the intake valve 5. The lower half of theside wall 9 is connected to the side wall 12 of the helical portion B atthe helix terminating portion C of the helical portion B.

As illustrated in FIGS. 1 through 5, bypass passages 14, branched offthe inlet passage portions A of the corresponding intake ports 6 andhaving a substantially uniform cross-section, are formed in the cylinderhead 3, and each of the bypass passages 14 is connected to the helixterminating portion C of the corrresponding intake port 6. Each of theinlet openings 15 of the bypass passages 14 is formed on the side wall 9at a position located near the inlet open end of the inlet passageportion A of the corresponding intake port 6, and each of the outletopenings 16 of the bypass passages 14 is formed on the upper end portionof the side wall 12 at the helix terminating portion C of thecorresponding intake port 6. In addition, valve insertion bores 17,extending across the corresponding bypass passages 14, are formed in thecylinder head 3, and rotary valves 18, each functioning as a flowcontrol valve, are inserted into the corresponding valve insertion bores17. The rotary valves 18 are inserted into the corresponding bypasspassages 14, and as illustrated in FIG. 9, each of the rotary valves 18comprises a thin plate-shaped valve body 19, and a valve shaft 20 formedin one piece on the valve body 19. The valve shaft 20 is rotatablysupported by a guide sleeve 21 fitted into the valve insertion bore 17.The valve shaft 20 projects upwardly from the top face of the guidesleeve 21, and an arm 22 is fixed onto the projecting tip portion of thevalve shaft 20.

Referring to FIG. 10, the tip of the arm 22 fixed onto the top end ofthe valve shaft 20 is connected via a connecting rod 43 to a control rod42 which is fixed onto a diaphragm 41 of a vacuum operated diaphragmapparatus 40. The diaphragm apparatus 40 comprises a vacuum chamber 44separated from the atmosphere by the diaphragm 41, and a compressionspring 45 for biasing the diaphragm 41 is inserted into the vacuumchamber 44.

An intake manifold 47, equipped with a compound type carburetor 46comprising a primary carburetor 46a and a secondary carburetor 46b, ismounted on the cylinder head 3, and the vacuum chamber 44 is connectedto the interior of the intake manifold 47 via a vacuum conduit 48, avacuum control valve device 49 and a vacuum conduit 50. As illustratedin FIG. 10, the vacuum control valve device 49 comprises three housings,that is, a first housing 51, a second housing 52, and a third housing 53which are interconnected to each other by using, for example, anultrasonic welding. A vacuum introduction chamber 54 is formed in thefirst housing 51 and connected to the interior of the intake manifold 47via the vacuum conduit 50. An interior passage 55, extending on the axisof the vacuum control valve device 49, is formed in the second housing52 and has a vacuum port 56 and an atmosphere port 57 at opposite endsthereof. As will be hereinafter described in detail, the atmosphere port57 has a flow area which is slightly larger than that of the vacuum port56. In the embodiment illustrated in FIG. 10, the atmosphere port 57 hasa diameter of 0.8 mm, and the vacuum port 56 has a diameter of 0.6 mm.The interior passage 55, connected to both the atmosphere port 57 andthe vacuum port 56, is connected to the vacuum chamber 44 of thediaphragm apparatus 40.

A check valve 58 for controlling the opening operation of the vacuumport 56 is inserted into the vacuum introduction chamber 54 formed inthe first housing 51. The check valve 58 comprises a valve body 59 forclosing the vacuum port 56, a spring retainer 60 supported by the valvebody 59, and a compression spring 61 inserted between the springretainer 60 and the upper wall of the vacuum introduction chamber 54 forbasing the valve body 59 towards the vacuum port 56. An air valve 62 isintegrally assembled to the vacuum control valve device 49 and has adiaphragm 63. A valve 64 for controlling the opening operation of theatmosphere port 57 is fixed onto the central portion of the diaphragm63, and the peripheral edge portion of the diaphragm 63 is held betweenthe second housing 52 and the third housing 53. An atmospheric pressurechamber 65 is formed between the diaphragm 63 and the second housing 52and is open to the atmosphere via an air introduction bore 66 formed inthe second housing 52 and via an air filter 67. The air filter 67 issupported by a cap 68 fitted onto the second housing 52. A vacuumchamber 69 is formed between the diaphragm 63 and the third housing 53and connected via a vacuum conduit 70 to vacuum ports 71 and 72 whichare open to the venturi portions of the primary carburetor 46a and thesecondary carburetor 46b, respectively. An adjusting screw 73 is screwedinto the lower end portion of the third housing 53, and a compressionspring 75 is inserted between the valve body 64 of the diaphragm 63 anda spring retainer 74 fitted onto the top of the adjusting screw 73 forbiasing the valve body 64 towards the atmosphere port 57.

The carburetor 46 is a conventional carburetor. Consequently, when theopening degree of a primary throttle valve 76 is increased beyond apredetermined degree, a secondary throttle valve 77 is opened. When theprimary throttle valve 76 is fully opened, the secondary throttle valve77 is also fully opened. The level of vacuum acting on the vacuumconduit 70 connected to the vacuum ports 71, 72 is increased as theamount of air fed into the cylinders of the engine is increased.Consequently, when the engine is operating at a high speed under a heavyload, that is, when the level of vacuum acting on the vacuum conduit 70becomes greater than a predetermined level, the diaphragm 63 of the airvalve 62 moves downward in FIG. 10 against the compression spring 75. Asa result of this, the valve body 64 opens the atmosphere port 57. Thus,the vacuum chamber 44 of the diaphragm apparatus 40 becomes open to theatmosphere. At this time, the diaphragm 41 moves downward in FIG. 10 dueto the spring force of the compression spring 45. Thus, the rotary valve18 is rotated and fully opens the bypass passage 14.

On the other hand, in the case wherein the opening degree of the primarythrottle valve 76 is small, since the level of vacuum acting on thevacuum conduit 70 is small, the diaphragm 63 of the air valve 62 movesupward in FIG. 10 due to the spring force of the compression spring 75.As a result, the valve body 64 closes the atmosphere port 57. Inaddition, in the case wherein the opening degree of the primary throttlevalve 76 is small, a great vacuum is produced in the intake manifold 47.Since the check valve 58 opens when the level of vacuum produced in theintake manifold 47 becomes greater than that of the vacuum produced inthe vacuum chamber 44, and since the check valve 58 closes when thelevel of the vacuum produced in the intake manifold 47 becomes smallerthan that of the vacuum produced in the vacuum chamber 44, the level ofthe vacuum in the vacuum chamber 44 is maintained at the maximum vacuumwhich has been produced in the intake manifold 47 as long as the airvalve 51 remains closed. If a vacuum is produced in the vacuum chamber44, the diaphragm 41 moves upward in FIG. 10 against the compressionspring 45. As a result, the rotary valve 18 is rotated and closes thebypass passage 14. Consequently, when the engine is operating at a lowspeed under a light load, the bypass passage 14 is closed by the rotaryvalve 18. In the case wherein the engine speed is low even if the engineis operating under a heavy load, and in the case wherein the engine isoperating under a light load even if the engine speed is high, since thevacuum acting on the vacuum conduit 70 is small, the air valve 62remains closed. Consequently, when the engine is operating at a lowspeed under a heavy load and at a high speed under a light load, sincethe level of the vacuum in the vacuum chamber 44 is maintained at theabove-mentioned maximum vacuum, the bypass passage 14 is closed by therotary valve 18.

In the vacuum control device 49 as illustrated in FIG. 10, the sizes ofthe atmosphere port 57 and the vacuum port 56 have a great influence onthe opening-closing action of the rotary valve 18, and if the sizes ofthe atmosphere port 57 and the vacuum port 56 are not suitablydetermined, there is a danger that the rotary valve 18 remains closedindependently of the amount of air fed into the cylinders of the engine.For example, in the case wherein the atmosphere port 57 and the vacuumport 56 are formed so that they have the same flow area, and wherein thediaphragm apparatus 40 is constructed so that the diaphragm 41 movestowards the vacuum chamber 44 when the level of vacuum in the vacuumchamber 44 becomes greater than about -70 through -100 mmHg, if the airvalve 62 opens when the level of vacuum in the intake manifold 47 isequal to about -300 mmHg, ambient air flows into the interior passage 55from the atmosphere port 57, and air in the interior passage 55 flowsinto the intake manifold 47 via the check valve 48. As a result of this,even if the air valve 62 opens, the pressure in the interior chamber 55does not become equal to the atmospheric pressure, but vacuum, having alevel which is equal to the intermediate level between the atmosphericpressure and vacuum produced in the intake manifold 47, for example,vacuum of -150 mmHg acts on the interior passage 55. Consequently, atthis time, since the level of vacuum in the vacuum chamber 44 of thediaphragm apparatus 40 becomes equal to -150 mmHg, the diaphragm 41 isretained at the uppermost position in FIG. 10. Therefore, a problemoccurs in that, even if the air valve 62 opens, the rotary valve 18remains closed.

On the other hand, in order to eliminate the above problem, if theatmosphere port 57 and the vacuum port 56 are formed so that theatmosphere port 57 has a flow area which is more than twice the flowarea of the vacuum port 56, since the air valve 62 cannot open, aproblem occurs in that the rotary valve 18 remains closed. That is,since the level of vacuum in the vacuum chamber 69 of the air valve 62is equal to the mean valve of vacuum produced in the venturi portions ofthe primary carburetor 46a and the secondary carburetor 46b, the levelof vacuum in the vacuum chamber 69 is small. Consequently, if a greatvacuum acts on the atmosphere port 57, since the force pulling the valvebody 64 upward caused by vacuum acting on the atmosphere port 57 becomesstronger than the force pulling the valve body 64 downward caused byvacuum acting on the vacuum chamber 69, a problem occurs in that the airvalve 62 cannot open.

As a result of repeatedly conducting experiments in order to eliminatethe above-mentioned problems, the inventor has proven that, if theatmosphere port 57 and the vacuum port 56 are formed so that theatmosphere port 57 has a flow area which is slightly larger than that ofthe vacuum port 56, it is possible to open or close the rotating valve18 in response to the opening and the closing operations of the airvalve 62, respectively. In the embodiment illustrated in FIG. 10, thediaphragm 63 of the air valve 62 has a diameter of about 23 mm. In thiscase, as mentioned previously, it is preferable that the atmosphere port57 and the vacuum port 56 have a diameter of about 0.8 mm and about 0.6mm, respectively. Of course, the optimum sizes of the atmosphere port 57and the vacuum port 56 are changed dependently of the number and thesize of the rotary valves 18. It has been proven that it is preferablethat the diameter of the atmosphere port 57 be in a range of 0.6 through1.5 mm, and the diameter of the vacuum port 56 be in a range of 0.4through 1.2 in an engine for use in a load vehicle. Of course, also inthis case, it is necessary that the atmosphere port 57 has a diameterwhich is slightly larger than that of the vacuum port 56.

As mentioned above, when the engine is operating at a low speed under alight load, that is, when the amount of air fed into the cylinder of theengine is small, the rotary valve 18 closes the bypass passage 14. Atthis time, the mixture introduced into the inlet passage portion A movesdownward, while swirling, along the upper wall 13 of the helical portionB. Then, since the mixture, while swirling, flows into the combustionchamber 4, a strong swirl motion is created in the combustion chamber 4.

When the engine is operating at a high speed under a heavy load, thatis, when the amount of air fed into the cylinder of the engine is large,since the rotary valve 18 opens the bypass passage 14, a part of themixture introduced into the inlet passage portion A is fed into thehelical portion B via the bypass passage 14 having a low flowresistance. Then, this part of the mixture collides head-on against themixture stream flowing along the upper wall 13 of the helical portion B.As a result of this, since the mixture stream flowing along the upperwall 13 of the helical portion B is decelerated, the swirl motion isweakened. As mentioned above, when the engine is operating at a highspeed under a heavy load, since the rotary valve 18 opens, the entireflow area of the intake port 6 is increased, and the swirl motion isweakened, it is possible to obtain a high volumetric efficiency. Inaddition, by forming the inclined wall portion 9a, the flow direction ofa part of the mixture introduced into the inlet passage portion A isdeflected downward. As a result of this, since the part of the mixtureflows into the helical portion B along the bottom wall of the intakeport 6 without swirling, the flow resistance of the intake port 6becomes small, making it possible to further increase a volumetricefficiency when the engine is operating at a high speed under a heavyload.

According to the present invention, it is possible to assuredly open therotary valve when the amount of air fed into the cylinders of the engineis increased beyond a predetermined value. In addition, since the levelof vacuum acting on the vacuum chamber of the diaphragm apparatus can becontrolled by an integrally formed single vacuum control valve device,it is possible to reduce the size of the flow control device and improvethe reliability of the flow control device.

While the invention has been described with reference to a specificembodiment chosen for the purpose of illustration, it should be apparentthat numerous modifications can be made thereto by those skilled in theart without departing from the spirit and scope of the invention.

I claim:
 1. A device for controlling the flow in a helically-shapedintake port of an internal combustion engine which has an intake passageconnected to said intake port and has a carburetor having a venturiportion, said intake port comprising a helical portion formed around anintake valve, and a substantially straight inlet passage portiontangentially connected to the helical portion and having a helixterminating portion, said device comprising:a bypass passage branchedoff from the inlet passage portion and connected to the helixterminating portion of the helical portion; normally closed valve meansarranged in said bypass passage for controlling the flow area of saidbypass passage; a vacuum operated apparatus having a vacuum chamber andconnected to said valve means for actuating said valve means in responseto a change in the level of vacuum produced in said vacuum chamber; andcontrol means having a vacuum port which interconnects said vacuumchamber to said intake passage, a check valve which cooperates with saidvacuum port and opens said vacuum port when the level of vacuum in saidintake passage becomes greater than that of vacuum in said vacuumchamber, an atmosphere port which interconnects said vacuum chamber toatmosphere and has a flow area which is slightly larger than that ofsaid vacuum port, a vacuum cavity connected to the venturi portion ofsaid carburetor, and an air valve which cooperates with said atmosphereport and is actuated in response to a change in the level of vacuumproduced in said vacuum cavity for opening said atmosphere port to opensaid valve means when the level of vacuum in said venturi portionbecomes greater than a predetermined level.
 2. A device according toclaim 1, wherein said bypass passage has an outlet opening which is opento the helical portion at a position near a top wall of the helicalportion.
 3. A device according to claim 1, wherein said vacuum operatedmeans comprises a diaphragm connected to said valve means and separatingsaid vacuum chamber from the atmosphere.
 4. A device according to claim1, wherein said control means comprises an interior passage havingopposite ends and an intermediate portion which is connected to saidvacuum chamber, said atmosphere port being formed at one end of saidinterior passage, said vacuum port being formed at the other end of saidinterior passage.
 5. A device according to claim 1, wherein saidcarburetor comprises a primary carburetor having a venturi portion, anda secondary carburetor having a venturi portion, said vacuum cavitybeing connected to both said venturi portions.
 6. A device according toclaim 1, wherein said valve means comprises a rotary valve rotatablyarranged in said bypass passage.
 7. A device according to claim 6,wherein said rotary valve comprises a thin plate-shaped valve bodyextending through said bypass passage.
 8. A device according to claim 1,wherein said atmosphere port has a diameter of 0.6 through 1.5 mm, andsaid vacuum port has a diameter of 0.4 through 1.2 mm.
 9. A deviceaccording to claim 8, wherein said atmosphere port has a diameter ofabout 0.8, and said vacuum port has a diameter of about 0.6.
 10. Adevice according to claim 1, wherein said control means comprises anatmospheric pressure chamber formed therein and connected to saidatmosphere port, and a diaphragm supporting said air valve andseparating vacuum cavity from said atmospheric pressure chamber.
 11. Adevice according to claim 10, wherein said control means comprises anintegrally formed single housing in which said check valve, said airvalve, said vacuum cavity, said atmospheric pressure chamber and saiddiaphragm of said air valve are arranged.
 12. A device according toclaim 1, wherein the intake passage portion has an inlet open endlocated furthest from the helical portion, said bypass passage having aninlet opening which is open to the inlet passage portion at a positionnear said inlet open end.
 13. A device according to claim 12, whereinthe intake passage portion comprises an upper wall, a bottom wall, afirst side wall located near the intake valve and a second side walllocated remote from the intake valve, said first side wall comprising adownwardly inclined portion located near the helical portion, and asubstantially vertical portion located near said inlet open end, theinlet opening of said bypass passage being formed on said verticalportion.
 14. A device according to claim 13, wherein the intake portcomprises a valve guide projecting into the helical portion from anupper wall of the helical portion and having a circumferential wall,said downwardly inclined portion being tangentially connected to thecircumferential wall of said valve guide.